KZ650 Bolt-On Swingarm Upgrade?

OK, I've done a lot of searching on this, but I don't see anything definitive.

First, I love the look of the factory Enkei 7 spoke wheels, so I'd want to go with a Kz1000P rear wheel (like Mark Wing did).

Second, I want to stay with a dual-shock setup, as I really like that look.

I've seen where people have done the Zephyr swingarm upgrade, although I'm unclear as to whether the 550 or the 750 is preferred, and I've found a lot of old posts both here and on kz650.info about the GS1100 swingarm, but it's not discussed much anymore. Is there a reason it's fallen out of favor?

Are there other options?

Which choice is best?

Thanks

There is no real "bolt on" swingarm. The closest would be the GS1100 at least with this one there is no fitting required just a few small washers.